1. Field of the Invention
The present invention relates to a side-lighting type surface light source device, a method for manufacturing the side-light type surface light source device, an electrooptical apparatus incorporating the side-light type surface light source device, and electronic equipment incorporating the electrooptical apparatus.
2. Description of the Related Art and Problems to be Solved by the Invention
FIG. 11 shows one example of a side-lighting type surface light source device employed in a liquid-crystal display device. A reflective sheet 4 is arranged on the underside of a light guide plate 3 in the side-lighting type surface light source shown in FIG. 11. A line light source 1 is arranged on an end surface 3a of the light guide plate 3. A reflector 2 is mounted to direct most of light rays from the light source 1 toward the end surface 3a of the light guide plate 3. The reflector 2 is formed, surrounding the light source 1 except the end surface 3a of the light guide plate 3, and thereby reflecting the light rays from the light source 1 toward the end surface 3a. The reflector 2 has opposed first end portion 2a and second end portion 2b, and the two end portions 2a and 2b are respectively overlaid on the front side and the back side of the light guide plate 3. The end portions 2a and 2b of the reflector 2 are respectively fixed to the front side of the light guide plate 3 and the back side of the reflective sheet 4 using both-side adhesive tapes 5a and 5b. 
Since the top and the bottom of the end portion including the end surface 3a of the light guide plate 3 are covered with the end portions 2a and 2b of the reflector 2 in the side-lighting type surface light source device having the above construction, the light rays from the light source 1 are prevented from straying from regions other than the end surface 3a of the light guide plate 3, and the light rays are effectively utilized. The side-lighting type surface light source device basically having such a coupling structure is disclosed in Japanese Unexamined Patent Application Publication No. 9-211450.
In the structure that affixes the light guide plate 3 to the reflector 2 using the both-side adhesive tapes 5a and 5b, a dedicated tool must be used with the components to be assembled (the light guide plate, the reflector, and the reflective sheet) aligned with the both-side adhesive tapes in an assembly process. The assembly process thus needs much attention and skill, and a number of assembly steps, and the assembly process itself is not so easy, requiring high costs.
The side-lighting type surface light source device having the above structure needs space for accommodating the both-side tapes 5a and 5b, respectively between the reflector 2 and the light guide plate 3, and between the reflector 2 and the reflective sheet 4, and the thickness of the device is accordingly increased. This presents a difficulty in an effort to promote a thinner design, although the demand for a thinner design is currently mounting in devices.
It is an object of the present invention to provide a side-lighting type surface light source device which is easy to assemble, has a small number of assembly steps, and is thin in the overall thickness thereof, and to provide a method for manufacturing the side-lighting type surface light source device. It is a further object of the present invention to provide an electrooptical apparatus and electronic equipment, each incorporating such a side-lighting type surface light source device.